Why C# allows methods/members to be public when the class is internal

Question

I have a class which I marked as internal and I marked fields and methods as public. It compiled without errors or warnings. Is there any specific need to have methods as public and class as internal (except when they are being implemented from interfaces or classes)?

Answer 1

It has no adverse effects, and also means that if you ever do decide to make the type public, you won't need to change the accessibility of your members.

Basically for a member:

• public means the member is visible to anyone who can see the Type.

• internal means the member is only visible in the current assembly, even if the Type is publicly visible.

So your choice would be based on which of these is most appropriate. In general it's most appropriate to make the members public (i.e. visible to anyone who can see the Type, i.e. part of the Type's public API). You would make members internal for the same reason you make members internal in a public class - typically helper members that should only be visible to "friend" classes in the same assembly, and don't form part of the public API.

In addition, an internal Type can derive from a public Type, so can inherit and override public members. Would it make sense to allow overridden public members, but not new public members?